1. Field of the Invention
The invention herein pertains to an insulated storage chest and particularly to a chest used to store and transport perishable items such as certain foods, biological materials and the like.
2. Description of the Prior Art and Objectives of the Invention
Insulated storage chests have been used for many years to transport food and other items in a temperature-controlled environment. Such chests generally employ insulated walls between which a heating or cooling device is placed proximate the food items. Such chests are useful and reliable for relatively short periods of time (2-4 hours). However, if perishable items are to be kept longer at specific temperatures, then often the perishable items have to be removed and the heating or cooling devices replaced or re-energized at periodic intervals to maintain the interior of the chest at the desired temperature. Such exchanges of the heating or cooling devices are oftentimes difficult, if not impossible, especially if the chest is being transported, for example, in an airplane where access to the chest is not available. Also, in remote field locations, re-energizing or replacing of the heating or cooling device may not be practical.
Even in chests which utilize a vacuum to prevent temperature fluctuations, problems arise because most conventional plastic coolers are slightly porous or otherwise leak, thereby causing the chest to lose its vacuum over time. In steel or metal chests with walls of the necessary rigidity and non-porousness, the cooler becomes too cumbersome to be easily transportable. Rough use may also damage or weaken the chests and thereby cause the vacuum to fail at an inopportune time.
Thus, with the disadvantages and problems associated with prior art insulated chests, the present invention was conceived and one of its objectives is to provide a portable, relatively lightweight storage chest for perishable items which will maintain a controlled and desired temperature level in excess of twenty-four hours under normal ambient temperatures.
It is still another objective of the present invention to provide an insulated chest and method which will greatly facilitate the storage and transportation of foods, biological materials and other items which require temperature control.
It is yet another objective of the present invention to provide an insulated chest which is pneumatically sealed for thermal security.
It is a further objective of the present invention to provide an insulated chest which will prevent convective and conductive heat transfer both in and out of the chest.
It is still a further objective of the present invention to provide an insulated chest which incorporates a conduit within a hinged cover which can be connected to a vacuum pump for sealing the chest and evacuating air from within the chest's container.
It is also an objective of the present invention to provide a chest in which the side walls and bottom have both an insulating material therebetween and a vacuum to increase the insulation rating.
It is another objective of the present invention to provide an insulated chest which has a sealed chamber within the side walls for maintaining a vacuum therein.
It is still a further objective of the present invention to provide a means for sealing a chamber between the chest's container compartment and the exterior surfaces of the chest to effectively maintain vacuum pressure even after rough or heavy use and handling.
It is yet another objective of the present invention to provide a plastic chest with a vacuum chamber in the side walls which is sealed to prevent the loss of vacuum pressure.
It is a further objective of the present invention to provide an insulated chest which receives a set of thermal control elements in order to maintain a desired temperature for an extended period of time.
It is still a further objective of the present invention to provide a set of interlocking cooling elements within the insulated chest which can maintain sub-zero temperatures for extended periods of time.
It is yet another objective of the present invention to provide a cooling element which changes color upon freezing so that a user can easily tell if the cooling element is charged visually.
Various other objectives and advantages of the present invention will become apparent to those skilled in the art as a more detailed description is set forth below.